1. (Field of the Invention)
This invention relates to a novel production process of highly concentrated extracts for food use.
2. (Prior Art)
In the case of extracts for food use which are broadly used in processed food, such as livestock meat extracts, poultry extracts, fish extracts, yeast extracts and the like, they are concentrated after their extraction from raw materials with the aim of reducing water activity and thereby effecting prevention of their putrefaction. However, when the water activity is adjusted only by means of concentration to about less than about 0.9, said value being generally said to be effective in preventing putrefaction, it is necessary to concentrate an extract to a Brix degree of about 70% or more, which causes a difficulty in effecting such concentration itself due to the foaming resultant from the increased viscosity, and the resulting highly concentrated extract is a gel form having poor fluidity and therefore is difficult to use. In general, therefore, in order to prevent putrefaction and secure fluidity of the product, concentration of an extract is held up at a Brix degree of approximately 40 to 50%, and the water activity is adjusted to approximately less than 0.9 by adding about 10 to 15% of sodium chloride to the extract concentrated to such a degree.
However, with the increasing intention for health and therefore for low salt food, development of salt-free extracts has been called for by processed food makers. In general, salt-free extracts are distributed by freezing them or after their retort sterilization or aseptic treatment, except for South American beef extracts which are concentrated to a Brix degree of as much as 80%.
Such beef extracts, however, are in the form of hard gel even at ordinary temperature and have no fluidity. Also, there is a problem of increased distribution cost in the case of freezing or increased initial plant and equipment investment in the case of retort sterilization and aseptic treatment. As it is universally known, the term retort sterilization means a heat-under-pressure sterilization treatment using sealed packing materials, and the term aseptic treatment means a treatment in which a sterilized product to be packed is packed in a previously sterilized container under aseptic conditions.